Apparatus for extruding metal



Dec. 5, 1939. c 1 E V ET AL 2,181,987

APPARATUS FOR EXTRUDING METAL Filed June 20, 1958 3 Sheets-Sheet 1 Dec. 5, 1939. c, J, BEAVER ET AL 2,181,987

APPARATUS FOR EXTRUDING METAL 3 Sheets-Sheet 2 Filed June 20, 1938 [W wzmww,

Dec. 5, 1939. c. J. BEAVER ET AL 2,181,987

APPARATUS FOR EXTRUDING METAL Filed June 20, 1958 3 Sheets-Sheet 3 F ig; 5.

PL457/C' M57744 INVENTORY-- 43W q wad WW g from which the ram which the plastic passages between Patented Dec. 5, 1939 Charles James field, Bowdon,

Beaver and Thomas James Fair- England, assignors to w. T. Glover and Company Limited,

Manchester,

England, a British company Application June In Gr 20, 1938, Serial No. 214,796

eat Britain June 23, 1937 6 Claims.

This invention relates to that type of apparatus for the extrusion of metal in which molten metal is fed into the outer part of a cylindrical container, is allowed to cool there and is then forced by a ram towards the inner end of the container, where it passes out in the plastic state by way'of a die or dies. In such apparatus, after the working stroke has been completed, the ram is drawn back relative to the container or vice versa and the further charge of molten metal is fed in to the space between the ram and the'remaining part of the previous charge at the inner end of the container. It will be seen that the operation of this apparatus is intermittent and it has been recognised that this kind of operation has many disadvantages.

By arranging two or more containers (each with its ram) to deliver into a single space, which may be spoken of as an extrusion chamber, from metal passes into the die and by making the working strokes of the rams at the appropriate time intervals it appears possible to produce a continuous output from the apparatus. But in order to do this, it is necessary to provide some means to prevent the working stroke of one ram from forcing back metal into a container has been withdrawn for the purpose of re-filling the container with molten metal. The metal in the delivery end of each container, and in the extrusion chamber, and the this and these, is in the plastic state. Accordingly, no ordinary mechanical valve can be used to prevent the backward movement of the material.

The present invention supplies an effective means of restraining the metal in the extrusion chamber from being forced back into a container when the pressure therein is reduced so that an effective multi-container press of the type indicated can be produced in which the containers can be filled in succession in the ordinary way, since there is no back pressure exerted on the metal in the container during filling and, in fact, no pressure is exerted there except that necessary for the working stroke. In accordance with the invention the backward movement is restrained by providing a particular disposition of the passages between the containers and the common extrusion chamber, this disposition being such thatthe metal'ilows easily from each container into the extrusion chamber, but is effectively prevented from moving to any substantial extent in the opposite direction.

It has been found that, under the ordinary working conditions of pressure and temperature and rates of movement which are used in extrusion apparatus of the kind indicated, a pronounced angle between the directions of flow of plastic metal in two passages or a passage and a chamber at the place where they join is sufficient to prevent metal of one stream from causing back flow in the other when the forward pressure therein ceases.

Accordingly, by arranging the passages leading from the delivery end of each container and into 10 the extrusion chamber in such a way that there is a pronounced difference between the directions of flow of the plastic metal at the junction, there is no tendency for the plastic metal to be forced back into the container from which the ram is withdrawn for the purpose of re-filling the container.

An angle of 90 or less between the directions of flow of two streams of plastic metal meeting in the extrusion chamber gives satisfactory results in practice. Angles larger than 90 would in general, result in some back flow.

It is to be noted that the invention is not-directly concerned wih the relative positions of the two or more containers, these may have their axes parallel to each other or inclined to each other or even in line with each other. The controlling influence, in accordance with the invention is the relative disposition of the passages from the containers to the extrusion chamber. 80 The desired result can be obtained by placing a pair of passages so that they enter the extrusion chamber in close proximity with their end 'portions making an appropriate angle with each other. Another arrangement which gives satisfactory results is one in which each passage enters a circular (or approximately circular) extrusion chamber tangentially and directed round the chamber in the same sense. The passages need not enter the chamber in close proximity, in this case, but may be spaced uniformly round the chamber (e. g., for two passages the entries would be diametrically opposite). The angle between the entering stream and the movement of adjacent metal round the chamber is a small one.

The invention is further described hereinafter, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a view partly in section of a twocontainer extrusion apparatus adapted for sheathing electric cables;

Figure 2 is a section on the line 11-11 in Figure 1 looking in the direction of the arrows;

Figure 3 is a diagrammatic representation of the metal streams entering the extrusion cha ber'of the apparatus shown in Figures land 2;

Figure'4. isj..a.further View of the lead'streams represented in Figure 3;

5 Figure 5 is a view in section of a portion of a modified form of apparatus embodying the features of the invention; and a Figure 6 is a. diagrammatic representation of the metal streams entering the extrusion champparatus shown in Figure 5, looking in the direction of the arrow VI.

The apparatus represented in Figure 1 is a double container press intended to be used for the application of a lead sheath l to an electric cable 2. The press comprises two cylindrical containers 3 and 4 mounted on a single die-block 5, and the axes of the containers are inclined at a sharp angle to the vertical to form a press of the so-called V-type. Molten metal passes into the container 3 from a reservoir 6 formed about the outer end of the container 3 and fed with molten metal by means of 1 a supply pipe 1. When themetal within the container 3 has cooled sufficiently to become plastic a ram 8 is lower end of a piston 9 operating'within a hyelraulic cylinder I!) mounted above and in line with container 3 by means of two tie-bolts ll.

The other container 4 is charged in a similar mounted on the container ,4 by means of tiebolts |6.'

into two passages l1 and I3, and that from the point. 22 through which the cable 2 progresses from the rear of the die block 5. The passages converge to meet, in pairs, in proximity to points which are diametrically opposed in the wall of the the container 3 converges with the passage I 9 diametrically opposed to the entry 23. From the in the form of a tube I about the cable 2.

5 "The containers 3 and 4 are discharged alternately so that there is a continuous flow of plastic metal through the dies. When the discharge from one container 3 is being completed, that is,

as the corresponding ram 7 stroke the discharge of the other container 4 is container 3 which is thereupon recharged with molten metal. 7 'cools at such a rate that it is in a suitable condition forathe next extrusion operation which will be commenced as the discharge of the other container 4 is being completed.

The pairs of passages I 1, l9 and I8, 28 converge at an angle which in the arrangement illustrated is about Figure 3 which indicates, in conguncticn with of metal, 21, 28, 29 and ,38-within those portions of the passages l1, I8, 20 respectively, which are adjacent the points oi entry into the extrusion chamber. It is conside ed for the purpose of illustration that metal 1 being extruded conditions are maintained during discharge of metal from the container 4 and re-charge of the a container 3.

Figures 5 and 6 indicate the relative disposition of the l extrusion chamber 38, and each is adapted to be discharged by moving a ram, such as the ram 39 in the extrusion chamber 36, inwards towards 45 the extrusion chamber 38. The containers 36 and 48 located centrally within the extrusion cham- 50 her 38. The containers 36 and 31 will be disthe stream of metal 32 extending ,from the charge of metal 33 in one container 31, and the other stream of metal 34 extending from the residue 35 of the charge in the other container 36. It is assumed for the purpose of the illustration that 60 the charge of metal 33 in one container 31 is being pressed as the stream of metal 32, in the As is shown in Figure 5 the two streams of the same sense irrespective of whichever stream is moving into the chamber. It is clear that there is a sharp angle between the converging directions of movement of the metal 3| in the chamber 38 and of the stream entering the chamber at the junction of each stream with the chamber. Thus the metal 3| circulating in the chamber 38 would be required to change its direction by a large angle, by passing round a sharp edge, before it could produce a reverse flow of the stream 34 away from the chamber. The same conditions will exist at the junction with the the extrusion pressureis removed therefrom and the chamber is being fed by the stream 34. In these conditions no back flow will take place.

In extrusion apparatus constructed in accordance with the invention the length of the end parts of the passages which converge upon each other or enter the extrusion chamber at an angle and which are substantially straight should be substantially greater than the width of the passage, preferably of the order of three times or more. In a practical example it has been found that a passage 6 inches (15 cms.) long of circular cross-section and of a uniform diameter of inch (2.2 cms.) is of satisfactory proportions. It is to be understood that the controlling influence in the present case is entirely distinct from that of the tapering passage described in the specification of United States application Serial No. 1'12,- 944. The two influences can be combined by the use of tapering passages appropriately inclined to each other, but a sufficient effect is obtained without such combination. A multi-container press can be produced having the feature of the invention, such press comprising a number of containers grouped around a common extrusion chamber and each connected with it by a passage or passages arranged in the manner indicated. Where such a multi-container press is to be used for sheathing an electric cable, the cable can be led into and through the centre of the group of containers by way of a passage leading to an inner die located in the centre of the extrusion chamber.

What we claim as our invention is:

1. In an apparatus for extruding plastic metal from a number of cylindrical containers adapted to be charged with metal from their outer ends and to be discharged, after the metal has cooled to a plastic state, from their inner ends successively at time intervals into a common extrusion chamber to produce continuous extrusion therefrom, the provision of a valveless passage extending from the inner end of each container to the common extrusion chamber, each passage having a cross-sectional area substantially less than that of the associated container and being so disposed that there is a pronounced difference between the directions of movement of two bodies of plastic metal at their junction, thereby preventing reverse movement of metal in any of the passages when pressure therein toward the extrusion chamber ceases.

2. In an apparatus for extruding plastic metal from a number of cylindrical containers adapted to be charged with metal from their outer ends and to be discharged, after the metal has cooled to a plastic state, from their inner ends successively at time intervals into a common extrusion chamber to produce continuous extrusion therefrom, the provision of a valveless passage extending from the inner end of each container to the common extrusion chamber, each passage having a cross-sectional area substantially less than that of the associated container and being so'disposed that the directions of movement of two bodies of plastic metal at their junction make an angle with each other which is not greater than 90, thereby preventing reverse movement of metal in any of the passages when pressure therein toward the extrusion chamber ceases.

3. In an apparatus for extruding plastic metal from a number of cylindrical containers adapted to be charged with metal from their outer ends and tube discharged, after the metal has cooled to a plastic state from their inner ends successive- 1y at time intervals into a common extrusion chamber to produce continuous extrusion therefrom, the provision of a valveless passage extending from the inner end of each container to the common extrusion chamber, each passage having a cross-sectional area substantially less than that of the associated container the length of each passage being not less than three times the width thereof, and each passage being so disposed that there is a pronounced difference between the directions of movement of two bodies of plastic metal at their junction, thereby preventing reverse movement of metal in any of the passages when pressure therein toward the extrusion chamber ceases.

4. In an apparatus for extruding plastic metal from a number of cylindrical containers adapted to be discharged successively at time intervals into a common extrusion chamber to produce continuous extrusion therefrom, the provision of a valveless passage extending from the inner end of each container to the extrusion chamber, the passages being tangentially joined with the extrusion chamber and directed in the same sense about the chamber.

5. An apparatus for extruding plastic metal comprising two cylindrical containers, means cooperating with each container to discharge plastic metal therefrom into a common extrusion chamber, two passages extending from each container to the extrusion chamber, each passage from one container converging with and meeting a passage from the other container at an angle of not more than about 90.

6. An apparatus for extruding plastic metal comprising two cylindrical containers, means cooperating with each container to discharge plastic metal therefrom into a common circular extrusion chamber, two passages extending one from each container to the extrusion chamber, the two passages being tangentially joined with the extrusion chamber at diametrically opposite points and being directed in the same sense about the chamber.

JAMES BEAVER. THOMAS JAMES F 

